Electron discharge device



J. 17, W3@. HI. E HOLLMANN 2,144,222

ELECTRON DI SCHARGE DEVICE Filed June 26, 1956 INVENTOR HANS ERICHHQLLMANN BY Wig WM} ATTO R N EY Patented Jan. 17, 1939 UNITED STATESamc'rnon mscnaaen nnvrca Hans Erich Hollmann, Berlin, Germany, assignorto TelefunkenGesellschaft fiir Drahtlose Telegraphic in.

of Germany IL, Berlin, Ge many, a corporation Application June 2c, 1936,Serial No. 87,386

. In Germany August 15, 1935 is claims. (01. 250-275) It is known thatby means of a concentrical tubularline acting as a resonance circuit ofan ultra-short wave transmitter, a much more favorable adaptation to thebuilding up resistance of 5. the oscillatory tube can be-attained, thanis possible with a simple double wire line. As a further advantage .oi.the tubular line, it is found that by connecting or inserting tubeelectrodes, no places of irregularity appear, and that the uniform dis-10 tribution of the capacity per unit length of the tubular line willnot be disturbed by the tube electrodes if the latter are properlyconnected to or inserted in the tubular line. This property of a tubularline not only produces a notable improvement in the useful eflect, butit also decreases the danger that due to reflections of the waves atirregular places existingin wire lines,

side waves may be created thus detrimentally' affecting the stability ofthe ultra-short transmitter.

The connection or insertion of a three pole tube to or in a concentricaltubular line does not cause any particular diiliculties, since the innertube can simply terminate into the grid and the outer 2!! tube into theanode. The tube electrodes are connected in asimple manner to thetubular line by having'the diameters of the tubular conduc: tors conformexactly to the diameters of the electrodes; difierent diameters may alsobe used,

it being necessary to take the precaution that the wave resistance (1.e., surge impedance) does not undergo a sudden change at the place oftransition, but that it is the same for the tubular conductor and torthe tube electrodes.

at Also in case of the magnetron which operates with the greatestefllciency, as is known, in the ultra short wave range, a tubularconductor as an excited oscillatory system is found toebe advantageous.In the case 01' a magnetron with solid wave 40 anode, the problem ofconnecting a tubular conductor can .be solved in a comparatively simplemanner, since in this case the anode may simply terminate into the outertubular conductor and the cathode into the inner tubular conductor, or45 both may form a partof the outer tubular conductor and innerconductor included in the concentric tubular line. The conditions aremore difficult in case of a magnetron with slotted anode of the typeproposed byHabann, in which, as is 50 known, the anode cylinder isdivided into two or several segments. The difficulties encountered inconnecting these two segments or groups of segments with a tubular line,are caused by the fact that the segments are situated on a single 5cylinder surface from where they must be brought to the two tubularconductors with diflerent diameters. This can be accomplished only bycomplicated bends and the like, thereby producing places ofirregularities which are just to be avoided by the tubular conductors.The claw- 5 like anode segments S and S" of Fig. la and the segmentsS'1, S: and S"1'ot Fig. 1b can be said to overlap each other, the termoverlap not being limited to, any particular arrangement whereby thesegments face each other but being 19 broad in its meaning to includeany dovetail or over-reaching arrangement of segments.

In order to overcome these drawbacks in the present invention, anarrangement will be described in which the outer tubular conductor or 16the inner one of a concentric double line is composed of two partshaving the same diameter, namely such that the axes of said parts form astraight through line. These two tubular pieces terminate at the endsfacing each other into seg- 20 ments which engage each other in themanner of claws, and thereby form the anode of a Habann tube. Beforedescribing the complete magnetron transmitter as completed by the secondtubular conductor of the concentric line, this basic idea of 25 thepresent invention will be elucidated by reference to Figs. 1a and 1b,which show details of an electron discharge device constructed inaccordance with the invention. Figs. 2 and 3 show, except for themagnetic field, complete details or 80 an electron discharge device inaccordance with the invention.

In Figs. la and lb, items R'i and R": represent the two tubular piecesof equal diameter coaxialiy arranged. At their ends facing each other,they terminate into the segments S and S" of Fig. la, which are sodimensioned that they do not come in contact with each other, but leavetherebetween the slots Z necessary for the production of oscillations.Fig. 1b shows the arrangement of 40 four segments, whereby each tubularpiece has two segments, the longitudinal cross section revealing,however, only three segments 8'1, 8'2 and S"1.

In order to complete the entire tube thus produced to a concentric lineby means of a second conductor, the arrangement may be such that thetubular conductors R1 and R"; form the I outer tubular conductor or theinner tubular conductor. At first the simplest case will be described inwhich inside of tubular conductors Ri and R"1 a coaxial conductor isarranged. The latter is designated by R2 in Fig. 1, and is soconstructed that it terminates in the center, i. e. within the segments,into the filament K. In order to establish oscillation nodes at the endsof the concentric tubular line, two metallic closing discs B1 and B: areprovided by means of which the line will be short circuited. Putting itanother way, discs Bi and B: are short circuiting discs which haveextremely low impedance to radio frequency currents. I

In order to evacuate the space between the seg ments, the entirearrangement can be placed into a vacuum vessel, or parts of thetubularline may be formed as parts of the vacuum vessel and may besealed up with suitable covers of glass and intermediate glass pieces. Aconstruction in which this is possible is shown in longitudinal crosssection in Fig. 2. Items Ri and R"; are again the two tubular piecesterminating into the segments S'and s", and in whose axis the centralconductor R: with the filament K are placed. Items B1 and B2 are againthe two closing bridges which in this case are capacitively subdividedto separate the plate potential. To achieve this end they consist of twometal discs, the one connected to the outer tubular conductors R'i andR"1, and the other one Joining the inner tube central conductor R2, saidmetal discs being electrically separated from each other by means of anintermediate insulating disc A1 or A2. Items P and P are two metallicend plates connected only to R: and which serve in known vmanner forabsorbing and deviating the electron current leaving the space betweenfilament and segments by the action of the magneticfield in the axialdirection. The two free ends of the outer tubular pieces R'1 and R"1 arenow closed up vacuum tight by means of two glass caps K and K". Thecentral conductor R: is passed through them in order to supply theheating voltage. Over the segments there is placed a short tube G ofglass or quartz, likewise connected vacuum tight with the two tubularpieces R'1 and R"1 by means of cone-shaped metal rings M and M. In thismanner a completely enclosed hollow space is produced that can beevacuated in the ordinary way. The magnetic field necessary in the axialdirection is obtained in the simplest manner, by means of a coil Csurrounding the tube.

- The condition of oscillation will now become such that a voltage loopappears in the center between the two short circuit bridges B1 and Ba.Owing to the capacity between the segments, and in view of theuninterrupted central through conductor, the outer tubular conductoracts unii'ormly as regards the electric waves, i. e. the two segments Sand S" will oscillate in equal phase. For the production ofoscillations, in this case only the negative building up resistancebetween the segments, acting as a closed anode cylinder, and thefilament play a part. In the slotted anode cylinder of the Habann tube,the negative building up resistance lies, however, be tween thesegments, and optimum useful eflect is obtained only when theoscillatory system to be excited by the magnetron lies between thesegments and produces thereat high frequency potentials of oppositephase.

In order also to accomplish this in the arrangement herein described, afurther mode of structure according to the idea of the invention isshown in Fig. 3, wherein the two tubes R'1 and R"1 together with theirsegments S and S" form the inner cylinder of a concentric tubular line,surrounded by a further metal tube which is again closed up by means ofshort circuit bridges Bi and Ba. This outer tube, just as in the case ofthe inner tube, is divided into two halves R: and R": maintained atproper space, in the example of construction herein described, by means01' a short spacer ring G of glass. The space between the two outertubular pieces, in other words the length of the spacer ring G, willsuitably be so chosen that the mutual capacity between R: and R": equalsthe capacity between the segments S and S", in order that the state ofoscillation of the tubular line will be possibly a symmetrical one. Thusthe entire tubular line between bridges Bi and B2 is divided into twohalves of which each can oscillate in M4, so that phase opposite highfrequency voltages will be produced at the -two segments S and S", or atthe corresponding groups of segments. The arrangement of the filament Kand of the end electrodes P and P" have remained the same as in the case01' Fig. 2. In this practical example, the vacuum vessel is formed of K,Ri, Bz, 'R'z, G, R":, Br, K", but this arrangement may also be providedwith a glass enclosure surrounding only the inner tubular conductor,such as shown in Fig. 2, whereby the advantage is obtained that the twobridges B1 and B: can be moved for the purpose of tuning.

It should be understood that the invention permits of numerous othercombinations of elements not specifically disclosed herein. The feedingand the putting in operation of this transmitter takes place in exactlythe same manner as in the hitherto known magnetron generators.

What is claimed is:

1. An electron discharge device comprising a pair of separated anodes inthe form of two coaxial metallic tubes of substantially the samediameter placed end to end, portions or said anodes near their adjacentends being cut away to provide overlapping separated segments, a cathodelocated in the axis of said anodes and having an effective portion inthe region of said overlapping segments of said anodes, and meanssurrounding said anodes in the region of said segments for producing amagnetic field.

2. An electron discharge device comprising a pair of separated anodes inthe form of two coaxial metallic tubes of substantially the samediameter placed end to end, portions or said anodes near their adjacentends being cut away to provide overlapping separated segments, a cathodelocated in the axis of said anodes and having an effective portion inthe region of said overlapping segments of said anodes, and a metallicplate connected to each terminal of the eflective portion of saidcathode for confining impact of said electrons to said segments.

3. An electron discharge device comprising a pair of separated anodes inthe form of two coaxial metallic tubes or substantially the samediameter placed end to end, portions or said anodes near their adjacentends being cut away to provide overlapping separated segments, a cathodelocated in the axis or said anodes and having an effective portion inthe region of said overlapping segments of said anodes, and a metallicplate connected to each terminal of the effective portion of saidcathode for confining impact 01' said electrons to said segments, saidcoaxial metallic tubes comprising the outer envelope of said device, andmeans surrounding said device at the location of said anode segments forproducing a magnetic field.

4. An electron discharge device comprising two coaxial metallic tubes ofsubstantially the same diameter placed end to end, the adjacent portionsof said tubes being cut away to provide for each tube a pair ofseparated segments facing each other, the segments of one tube occupyingthe spaces between segments of the other tube, a cathode locatedsubstantially in the axis of said tubes and having an effective portionin the region of said segments, said segments comprising anodes for saiddevice, and means for producing a magnetic field in the space betweensaid segments.

5. An electron discharge device comprising a pair of coaxial metallictubes 01 substantially the same diameter placed end to end, each of theadjacent portions of said tubes having a segment forming an anode, acathode located in the axis of said tubes and having an efiectiveportion in the region of said segments, and means for producing amagnetic field in the space between said segments.

6. An electron discharge device comprising a pair of coaxial metallictubes of substantially the same diameter placed end to end, each of theadjacent portions of said tubes having a segment forming an anode, acathode located in the axis of said tubes and having an efiectiveportion in the region of said segments, and leads extending in the samestraight line as said cathode for connecting the terminals oi! saidcathode to a circuit located externally of said device, each of saidleads being located within one of said tubes, and means within saiddevice having low impedance to radio frequency energy coupling each leadwith its associated metallic tube surrounding it.

'7. An electron discharge device in accordance with claim 6, whereinsaid low impedance means consist of metallic discs.

8. A magnetron comprising a pair 01! coaxial metallic tubes ofsubstantially the same diameter placed end to end, each of the adjacentportions of said tubes having a-segment forming an anode, a cathodelocatedin the axis of said tubes and having an effective portion in theregion said segments, an envelope surrounding said tubes for 9, portionon both sides 0! said segments, means effectively closing the ends oi.said tubes remote from said segments whereby said tubes and envelopeform an evacuated electron discharge device, and means for producing amagnetic field for influencing the path citravel of the electrons I,emanating from said cathode.-

9. A ,magnetron in accordance with claim 8,

.wherein said envelope is made of glass and said --tubes form walls forsaid evacuated electron distions placed end to end and comprising a partof an evacuated envelope for said device, and means having low impedanceto radio frequency energy located near each end of said coaxial tubesdirectly connecting same to said outer tube.

11. An electron discharge device comprising a pair of coaxial metallictubes of substantially the same diameter placed end to end, each of theadjacent portions of said tubes having a segment forming an anode, acathode located in the axis of said tubes and having an effectiveportion in the region of said segments, a concentric outer conductivetube surrounding said coaxial tubes for the greater portion of theirlength, said concentric outer tube being divided into two portionsplaced end to end which comprise a part of an evacuated envelope forsaid device,

12. An electron discharge device comprising a pair of coaxial metallictubes of substantially the same, diameter placed end to end, each of theadjacent portions of said tubes having a segment forming an anode, acathode located in the axis of said tubes and having an effectiveportion in the region of said segments, a concentric outer conductivetube surrounding said coaxial tubes for the greater portion of theirlength, said concentric outer tube being divided into two por-' tionsplaced end to end which comprise a part of an evacuated envelope forsaid device, and means of low impedance to radio frequency energyconstituting metallic discs which are movable over the inner surface ofsaid outer conductive tube and the outer surface of said inner tube.

13. An evacuated electron discharge device comprising inner and outerconcentric electrically conductive tubes forming an oscillatory circuit.said inner tube being divided into two portions placed end to end, meansnear the outer ends of said portions of the inner tube and connected toboth inner and outer tubes for tuning same, and electron emitting meanslocated in the interior of said inner conductive tube. i

14. An evacuated electron discharge device comprising inner and outerhollow concentric conductive tubes forming an oscillatory circuit, aconcentrically arranged cathode located near the center of and withinsaid inner tube, said inner tube being divided into two portions placedend to end, and means near the remotely located ends of said inner tubeand connected to both hollow tubes for tuning same.

15. Magnetron transmitter comprising an evacuated electron dischargedevice including a concentric tubular line having two conductive tubesof the same diameter terminating at the ends facing each other into twooverlapping segments, said segments being physically separated from oneanother and forming anodes for said device, a cathode located in thespace between said segments, and a coil surrounding said electrondischarge device for producing a magnetic field.

muss ERICK Hon-MANN.

